Recently, low-molecular weight polyalkoxysiloxane compounds having alkoxyl groups, such as those obtained from partial hydrolysis/condensation of tetramethoxysilane, tetraethoxysilane, tetrabutyoxysilane or the like, are used with increasing popularity in the industries. For instance, "MKC Silicate MS51" and "MKC Silicate MS56" are produced and sold by Mitsubishi Chemical Corporation as partial hydrolysis/condensation products of tetramethoxysilane. These partial hydrolysis/condensation products of tetramethoxysilane are added to the existing coatings, coating solutions to be applied for surface treatment of powders and various other types of bases, and resin compositions containing fillers such as inorganic powders, for the purpose of providing the useful functions such as stain resistance, weather resistance, scratch resistance, acid resistance and heat resistance to the coats or coating films.
However, addition of such partial hydrolysis/condensation products of tetramethoxysilane to the coatings, coating solutions or resin compositions may affect their storage stability. Specifically, such addition is causative of such problems as increase of viscosity and inducement of caking of the coatings or coating compositions during storage or in the course of preparation thereof.
"Ethyl Silicate ES40" Colcoat Co., Ltd. etc., as partial hydrolysis/condensation products of tetraethoxysilane, and "MKC Silicate BTS" (Mitsubishi Chemical Corporation), etc., as partial hydrolysis/condensation products of tetrabutoxysilane are commercially produced and sold. These alkoxysilanes and their partial hydrolysis/condensation products have little probability of causing rise of viscosity or caking when added to the said coatings. In some cases, however, they fail to show their effect of providing the envisioned functions, such as stain resistance, scratch resistance, heat resistance, etc., to the finally obtained coats. Especially, the coats would prove unsatisfactory in hardness.
It has been desired to offer the partial hydrolysis/condensation products of alkoxysilane compounds which, when blended in coatings, can maintain or improve their storage stability and compatibility and also contribute to providing such functions as stain resistance, weather resistance, scratch resistance, acid resistance and heat resistance to the finally obtained coats or coating films.
Especially when these alkoxysilanes or their partial hydrolysis/condensation products are blended in the water-based coatings, there would arise such problems as reduced compatibility of the components, increase of viscosity, gelation, and even cissing in the coats or coating films, resulting in marred appearance of the coats, and these problems have been a bar to utilization of the said products for water-based coatings. In recent years, solvent-based coatings has been changed to water-based ones for the benefit of environmental protection and safety, and accordingly it has been required to provide the partial hydrolysis/condensation products of alkoxysilane compounds which, when blended in water-based coatings, won't impair their storage stability and show an outstanding effect in providing such functions as stain resistance, weather resistance, scratch resistance, acid resistance, water resistance and solvent resistance to the coats.